Digital TV jargon buster

There are a lot of technical terms and abbreviations around digital TV. Here's what some of them mean.

3D Television - Some TV programmes and some Blu-ray discs are available in 3D format. To experience these you will need a 3D TV with special glasses, and for Blu-rays you will also need a 3D ready Blu-ray player.

Analogue - The way our television was transmitted and recorded traditionally before the digital switchover. It's called analogue because the electrical signal 'represents' the picture and sound signals rather than being coded into a series of 1s and 0s.

Assisted retune - This is a feature available on a some Freeview set-top boxes that automatically prompt you to initiate a retune when required. (Related article: Retuning and updating)

Audio description - Audio description describes what is happening on screen for those who have difficulty seeing. It's an additional narration that fits between dialogue and describes action sequences, body language, facial expression, costume and scenery. Audio description is broadcast only on selected programmes, and only some digital TVs and set-top boxes can decode these signals.

Broadband - A transmission with high bandwidth, so the data is delivered quickly. The term broadband is usually associated with internet access (eg ADSL or cable) and usually means faster access.

CRT (Cathode Ray Tube) - A CRT TV is an old-fashioned TV-tube television. Bulky and heavy compared to modern flat-panel TVs, but still capable of producing high-quality pictures.

DAB (Digital Audio Broadcasting) - The DAB service is radio's equivalent of digital TV. Many radio stations are also broadcast alongside the digital TV service, so can be received on digital TVs and set-top boxes.

Digital Television Recorder - A smart digital receiver that records programmes to a hard drive (like a computer saves information) or a DVD disc instead of on a video tape. Programmes you want to record can be selected directly from the on-screen TV guide (or EPG).

DTR - Abbreviation for 'digital television recorder'.

DTT or DTTV (Digital terrestrial television) - Digital TV signal transmitted through an aerial. In the UK, this includes the Freeview service (which includes the traditional terrestrial channels, BBC One, BBC Two, ITV, Channel 4 and Channel 5, and newer BBC, ITV and Channel 4 services) and additional commercial free and subscription services.

DTV - Abbreviation for 'digital television'.

DVB (DVB-C, DVB-S, DVB-T) - Digital Video Broadcasting, a European standard for digital television technology: DVB-C for cable, DVB-S for satellite and DVB-T for terrestrial.

DVD (Digital Versatile Disc) - Though they may all look the same, DVD discs come in many forms (hence the word versatile). The most popular (usually simply referred to as DVDs) are discs containing pre-recorded films, concerts or music videos. Other formats include DVD+/-R, DVD+/-RW and DVD-RAMs, which can be used at home to record TV programmes or computer files.

EPG (Electronic Programme Guide) - The on-screen TV guide provides a listing of TV channels and programmes, and is available for terrestrial, satellite and cable TV. You can use it to switch to the programme you want, or to select a programme to record. The information is sent by the broadcasters with 7 to 8 days worth of programming. Different brands of digital TV or set-top box may display this information in different ways.

freesat - The free satellite service provided by the BBC and ITV. There is also the similarly named Freesat from Sky.

Freeview - The main UK digital terrestrial television service that is transmitted through an aerial. No subscription is required but additional subscription services are available.

FTA (Free-to-air) - A programme or service that you don't need a subscription to get. FTA digital TV is available from terrestrial and satellite services.

Hard drive digital TV recorder - Sometimes called a personal video recorder (or PVR), this is a smart digital receiver that records programmes to a hard drive (like a computer saves information) instead of on a video tape. Programmes you want to record can be selected directly from the on-screen TV guide (or EPG). PVRs also allow you to pause and rewind live TV. The better PVRs incorporate twin tuners that allow you to record one programme while watching another.

HDMI - A digital audio and video connection that is capable of transmitting both standard- and high-definition TV signals. Typically used for connecting a 'Freeview HD' or a 'freesat HD' set-top box or a Blu-ray player to an 'HD Ready' TV. Some standard DVD and set-top boxes players can also be connected via the HDMI leads but this does not result in an HD picture. Some more advanced HDMI connections have a system called CEC, which allows your TV remote control to also operate the connected devices.

HD ready TV - A TV that has a screen resolution (of at least 720 horizontal lines) that's good enough to display high-definition TV programmes and high-definition discs (HD-DVD and Blu-ray). Also available is HD Ready 1080p of 'Full HD' TV, which is a TV that has a screen resolution (of at least 1080 horizontal lines) that's excellent for high-definition TV viewing. But for HD TV programmes you will still need a set-top box or digital TV recorder with a built in HD tuner to receive them.

a broadcasting standard that gives you a crisper picture and the opportunity of better quality sound than standard-definition TV;

a TV set that receives and displays high-definition TV channels using its own built-in HD tuner.

iDTV (Integrated Digital Television) - A TV with a built-in digital receiver. The term isn't really used anymore, now that all new TVs are digital TVs.

Interactive - This covers any system where the user can choose extra services or respond to events. For instance, you can select and watch a particular sporting event from a multi-screen selection, find out more information about a TV programme and get some of the same features that used to appear on teletext. For satellite and cable services, you might also be able to cast a vote or take part in a quiz.

Internet TV - This is a TV that connects to you home network and to the internet. The connection to the network may be via a wired cable or via Wi-Fi (wireless). The TV will typically access selected internet features such as BBC iPlayer and services such as YouTube, Flickr, etc.

IPTV (Internet Protocol TV) - A TV service delivered over the internet by phone line or cable. As it is via the internet, it means you can 'tune in' to selected TV or radio stations or programmes from anywhere in the world, but quality may not be as good as dedicated cable or phone line services such as Video on Demand (VOD).

LCD (Liquid Crystal Display) - LCD TVs are the most common type of flat-panel television. All screen sizes above 26" are suitable for displaying HDTV. Conventional LCD TVs use a form of fluorescent tube lamp backlight to illuminate the picture on the screen. Models that instead use semiconductor LED lamps for the screen's backlight illumination are called 'LCD TVs with LED backlights'. These generally provide better image quality, lower energy consumption and thinner televisions than conventional LCD. Though sometimes advertised as 'LED TVs', they're different from a true LED TV - which use a different technology. See also LED (below) and Plasma.

LED (Light Emitting Diodes) - An LED TV is one where the screen consists of an array of many LED semiconductor lamps. These types of screen are not generally available on the consumer market. They're typically used for very large screens found in public places and produce a bright image that can be seen at a distance. For the domestic TV models marketed as LED TVs, see LCD (above).

Modulator - An electronic gadget built into some set-top boxes and digital TV recorders that allows them to be connected to a TV using an aerial lead instead of the preferred SCART lead. It's useful for very old TVs with no SCART socket, but it means slightly lower picture quality and mono sound. You can also buy external modulators from specialist electronics shops that can be used with any set-top box.

Multiplex - A digital TV multiplex is created by bundling together a group of digital TV stations so that together they fit into one broadcast channel, rather than each requiring its own separate channel for transmission.

Pay-per-view - This is when you pay for particular films or sporting events on top of subscriptions to satellite or cable/phone line television.

PC card / adaptor - You can turn your computer into a digital TV and watch programmes on its screen. For this, you need to either install a digital TV PC card (this means getting inside the computer) or, if you have a modern PC with a fast USB-2 socket, you can plug in a digital TV USB adaptor. You use the supplied software to tune in and watch TV.

Plasma - A plasma TV is a particular type of flat-panel TV. They are popular for larger screen TVs (such as 42" or greater). Broadly speaking, plasma televisions give good picture quality, comparable to LCD TV, the main alternative. All recent plasma TVs are suitable for displaying HDTV.

Platform - A general term for the way of delivering or receiving digital television. Typical platforms are terrestrial, cable, satellite and TV delivered over a telephone line.

Red button - One of the four colour-coded buttons on your remote control for selecting interactive television services. For interactive features, broadcasters often prompt you on screen when to press the red button.

Regional preferences - This feature is designed to help you when you tune in your TV or box in an area that is served by more than one transmitter. During the tuning-in process, it offers you the choice of transmitters so you can select the strongest signal, the most channels or select your preferred TV region.

SCART cable - A common way of connecting one TV product to another that combines the picture and stereo sound in one plug. Very old TVs may not have a SCART socket, so for these you'll need a set-top box that incorporates a modulator so that you can connect the set-top box using an aerial lead.

Set-top box - The equipment that receives digital television and converts it so it can be received on an older TV or VCR. Occasionally abbreviated as 'STB'.

Switchover - The name used when broadcasters switched from analogue signal to digital by switching off the analogue transmitters.

Terrestrial TV - TV transmissions that are broadcast over the air directly to your TV aerial.

Top Up TV - A pay-TV company that provides extra channels and programmes on digital terrestrial TV. To receive the basic service, your digital TV equipment must have a slot or hole to take the Top Up TV viewing card or module respectively. All digital TVs should have a slot for this (or similar services) but not all set-top boxes do.

VCR (Video Cassette Recorder) - The machine used for recording and playing video tapes. Because a VCR has only an analogue tuner built in, you need to use it with an external set-top box to record digital TV.

VOD (Video on Demand) - Films and TV programmes you want to watch are delivered when you want to watch them, delivered via broadband phone line, cable or satellite. You can usually choose from a large library of films or programmes.

Widescreen - The ratio of the width to the height of a widescreen TV picture is 16 to 9, often called 16:9 format. Nearly all TV channels make and broadcast their programmes in widescreen format. Older programmes were in the narrower 4:3 format. If set up correctly, a widescreen TV and set-top box should display the picture on your screen in 16:9 or 4:3 as appropriate for the programme.

Y splitter - This is a simple gadget designed to split your rooftop TV aerial's signal into two. You plug your aerial cable in one end and then run two extension leads from the output sockets. Because it splits the signal without amplifying it, you'll end up with two weaker signals. But this shouldn't be a problem if you have a strong signal to start with. These splitters won't work for weaker signals, or if you want to split your signal more than two ways. For that, you'd need an aerial distribution amplifier.